Manufacture of lubricating oil



P 5 w. K. T. GLEIM 2,905,624

MANUFACTURE OF LUBRICATING OIL Filed NOV. 7, 1955 Dehydrogenolion And Hydrogenation Zone Aromofio' Separation Zane Finishing Zone 7 /0 Proouo/ 7 Product //v VE/V T01? Produo William K. 7: Gie/m y {M 9. ATTORNEY:

zw 6P United States Patent MANUFACTURE OF LUBRICATING OIL William K. T. Gleim, Island Lake, Ill.,.assignor, by mesne assignments, to Universal Oil P fqducts Company, Des Plaines, 111., a corporation of Delaware Application November 7, 195.5, SerialNo. 545,262

Claims. (Cl.v 20889) This invention relates. to a process. for the manufacture of lubricating oil and in particular. to. a novelprocess for treating a petroleum fraction. to. recover a lubricating oil therefrom which has properties superior to presently available lubricating oils.

As a general rule the components of a petroleum frac-. tion which possess lubricating properties are-.the, par--v affinic and isoparafiinic hydrocarbons. Aromatic or alkyl' aromatic hydrocarbons destroy. the lubricating quality of an oil fraction containing them and are therefore undesirable. The normal paraffinic constituents of a lubricating oil have a higher melting point than the isoparafiinic constituents and therefore yieldioils which havepoor temperature characteristics in. spite of good lubricating characteristics. Condensed ring naphthenic compounds have poor lubricating properties and also have an adverse effect on the viscosity index of the oil. Naphthenic compounds. which boil in the lubricating oil. range and which are not condensed have no .pronounced effects.

Previoustreatments. ofpetroleum. fractions to produce lubricating oils have consistedylargely of a separation of aromatic hydrocarbons from nonaromatic hydrocarbons which. is. followed by dewaxing, the latter process removing high. molecular Weight normal paraiiinic constituents that are normally solids, followed; by color improvingprocesses such as. clay. treating or acid: washing. The lubricating oil thus produced has. reasonable.lubricating. propertiesbeing rich. in, isoparaffinic compounds, but the condensed ring naphtheniccompounds give itpoor viscosa ity characteristics and; chemical instability.

Although an, oil; has good lubricatingproperties as manufacture, when it; is us,ed,-f.or exampla. in;.a..cr;anl-:-. case it is subjected to high temperature contact with metals such asiron, chromium molybdenum, .uicltel,v etc, hich m als, al h g sed s ructu al y as; componen s; of iron and steel, still retain hell",VfillElil'lOY/Ilt catalytic, properties. In; addition to;.-be ing, in centact withthese: catalytic materials, the; crankcase is; filled withgloxygen, nitrogen, and other; constituents to be; hercinaftcrt.dc-v scribed, The originalpe troleurrn fraction-usually-.co ntains small amounts of impuritiessuch as hydrocarbon mole.- Cules with combined, sulfur, nitrogen, oxygen, halogen or other material. These materials decompos under; theconditions in the crankcaseto form: oxidesor hy-- drides of the non-hydrocarbon portionofi the molecule. thereby introducing. into.- the; crankcase. suchi materials as sulfur oxides, nitrogen oxides water,hydrogensulfide, etc. As a result, corr.osive acidsolutionsare present dur ing the operation ofthe vehicle withthewell-known effect upon engine parts.

The presenceof acidic materials and; catalytic metals at. high temperature in thevcrankcase ofvv an,- automobile will cause the conversion of hydrocarbons. A most. read. ily; effected conversion at these conditions is the de hydrogenationof. polynuclear naphthenic compoundsto form. their corresponding aromatic,compounds-and other reactions which. may occuninclude; cracking, condens a tion reactions and others. These reactions or any com- 2. bination of them will obviously change the composition of the oil.

The condensation reactions, besides changing the composition of the oil, cause the formation of heavy material which is generically known as sludge. This extremely viscous or solid material fouls the valves and piston rings. of the engine.

It is an object of this invention to prepare. a lubricating oil that not only has superior lubricating qualitiesbut is prepared by a specific combination of steps to anticipate crankcase conditions and retain good lubricating qualitiesduring use. This object is accomplished. by treating an oil fraction with a combination of specific steps to regulate its composition to contain only constituents which have good lubricating qualities. and leave. out those which form undesirable material.

In line with accomplishing this object, it has beenobserved that condensed ring naphthenes have very poor Viscosity characteristics and poor lubricating qualities- These compounds dehydrogenate easily to form. condensed ring aromatic compounds. which in turn condense further to form gum, tar, varnish, carbon or sludge as hereinbefore described.

It is, therefore, an embodimentcf this invention to provide a process for the manufacture of lubricating oil Which comprises contacting a hydrocarbon oil. fraction boiling above 550 F. with a nonracidic supported. hydrogenation catalyst in the presence of hydrogen atconditions to cause dehydrogenation. ofcondensed ring naphthenic compounds, separating the resultant material into. aromatic and nonaromatic fractions and recovering thev desired lubricating oil from said nonaromatic fraction.

In a more specific embodiment this invention provides a. process for the manufacture of lubricating oil which. comprises contacting a hydrocarbon oil fractionboiling. above 550 F. with a. desulfurization catalyst in the presence of. hydrogen. atsuperatmospheric pressures. and at desulfurizing: con-ditions, separating theadesulfurized ma terial into .a normally liquidand a normally gaseous fraction, passing the liquid'fraction into-contact withahydro genationcatalyst supported. on: a. non-acidic: base in the presence ojE-hydrogen at. conditions to. cause dehydrogenae tion of condensed: ring naphthenic: compounds, separating the. resultant material-into aromatic; and nonaromatic fractions and: recovering the desired lubricating oil from saidnonaromatic fraction;

The process. of this invention may. he better'describedi withareference. to; the accompanying drawing; which shows; a flowdiagram ofzthe; process in. schematic" form. This: description is' notsintended as, limiting, upon the; invention but only as. being.illustrativesthereof. and itnis lIltClldBdi that all equivalent substitutions. of one: means for another are included within its: broad. scope. Y

The charges-stock. passes throughrline. 1: to impurity-res. movalzone 2'. This charge stock: is:a' hydrocarbon; trace tion preferably boilingbetween. 550- and 950 E. and atv leastin excess, of. 500 F. Its; source; will? usually bepetroleurn: which will usually be a: selected fraction dis? tilled from a crude, but may; be, previously treated: mate: rial such. as cyclev stock, however, the fraction. maybe. obtained from-the distillates resultingtfrom coke productionor from shale, oil.sands.or. any-other source.of.hy drocarbonw. material. It is preferred. when producing lubricatingoilz that: thechargezstock. be a paraflinic petro leum'; fraction or at least afraction. thata has. been devasphalted prion to; treatment by such means. as propane deasphalting. Ittisusually desirable to=dewax the charge tothe; process prior to this treatment: for the purpose of removing material from the process which will: notzbe-i benefited by the process auditor, the purposeflofg-recover 8; waxy. qht a uable: product: in its. own'i right.

The charge stock passing into the impurity'rmoval zone 2 is first heated to a temperature of between 400 F. and 650 F. and commingled with a hydrogen-containing gas at a pressure of from about 200 psi. to about 1000 psi. or more. The desulfurizing zone will contain a catalytic material Which is adapted to desulfurization. Such materials generally are compounds having hydrogenation activity but which are resistant to sulfur poisoning. Typical of such materials are the metals of group VI and group VIII of the periodic table which are catalytic in the form of the elemental metal and in the form of its oxide or sulfide. As is well known in the chemical art, catalyts employing these rather valuable metals can be made with great economy of material without sacrificing activity by disposing the metals on a suitable inorganic oxide support having high surface area and adsonptivity. Therefore, the preferred catalyst for use in impurity removal zone'2 is a metal such as tungsten, cobalt, molybdenum, chromium or mixtures thereof, preferably mixtures of cobalt and molybdenum disposed on a porous inorganic oxide support such as silica, alumina, zirconia, magnesia or combinations thereof, but preferably alumina or alumina stabilized with a small amount of silica.

The petroleum fraction passing through the impurity removal zone at the stated conditions is substantially unchanged by the contact with a catalytic material in all respects except that its composition with regard to sulfur, nitrogen and oxygen is drastically reduced. The impurity removal zone causes the molecules bearing sulfur, nitrogen or oxygen to decompose into hydrogen sulfide, ammonia and water and the corresponding saturated hydrocarbons. The impurity removal zone will also contain means for separation of the normally gaseous from normally liquid material resulting from this zone and will pass the normally liquid material via line 3 to hydrogenation and dehydrogenation zone 4. The normally gaseous material from impurity removal zone 2 may be vented, recirculated or partially vented and partially recirculated as the economy of the process dictates.

Hydrogenation and dehydrogenation zone 4 contains a catalyst having high hydrogenation activity supported on a non-acidic base. This composite catalyst results in a catalyst which will have activity only towards dehy drogenating and hydrogenating hydrocarbons but will not promote cracking, dehydrocyclization or dealkylation reactions. This catalyst is preferably a supported platinum or palladium catalyst with a support comprising a nonacidic base. A non-acidic base may consist of such inorganic oxides as alumina, silica, zirconia, magnesia, naturally occurring clays, kieselguhr or mixtures such as silica-alumina, silica-magnesia, etc., however, these mate rials if not catalytically inert by nature should first be treated with steam, alkali carbonate, hot water or ammonia or other reagents to deactivate them. To avoid destroying the high surface area of the base, it is preferable to composite it with alkaline or alkaline acting material such as alkali metal oxides, alkaline earth metal oxides, amines, ammonia or the like to impart thereto an alkaline quality thereby insuring a lack of acidity. Another suitable base material may be carbonaceous innature such as coke, coal, activated charcoal, etc., which material generally has high adsorptive qualities but which is inert regarding cracking or catalytic qualities.

The metal constituent having high hydrogenating activity which may be platinum, palladium, nickel, cobalt, molybdenum, tungsten, etc., but preferably platinum or palladium, may be composited with the non-acid base by any of the well-known means such as by impregnating the base with a solution of a soluble salt of the catalytic metal, drying and calcining the thus impregnated base to result in the deposition of the oxide of the catalytic metal thereon.

Hydrogenating and dehydrogenating zone 4 is maintained at carefully controlled conditions to cause the de- 4 X hydrogenation of condensed ring naphthenes and the hydrogenation of unsaturated aliphatic com-pounds. By contacting the hydrocarbon with the catalyst in the presence of hydrogen at a temperature of from about 500 to about 900 F., the desired reactions may be effected when using an active catalyst such as platinum or palladium. When a desulfurization zone, as in this embodiment, precedes the hydrogenation and dehydrogenation zone, a highly active but impurity-sensitive catalyst such as platinum or palladium may be employed over long periods of time without adverse effects.

The material passing from hydrogenation and dehydrogenation zone 4 will consist of parafiinic and isoparafiinic hydrocarbons in substantially the same condition as when they entered the process. If the charge to the process contains unsaturated aliphatic material, this will be saturated and will become part of the parafiinic and isoparaflinic hydrocarbons. Non-condensed naphthenic compounds or parafiinic compounds with naphthenic side chains are not as readily dehydrogenated as condensed ring naphthenes which will be dehydrogenated to form aromatic or alkyl aromatic compounds. The effluent may also contain hydrogen gas and some lower boiling hydrocarbons such as those boiling in the kerosene, gasoline or lower boiling range which result from a small amount of cracking or dealkylation. The total eifluent is passed to a receiver and separated into 2. normally gaseous fraction and a normally liquid fraction. The normally gaseous fraction may be recycled at least in part to the hydrogenation and dehydrogenation zone and the normally liquid portion passed through line 5 to aromatic separation zone 6.

In aromatic separation zone 6, a separation by hydrocarbon type is effected to remove aromatic hydrocarbons and unsaturated hydrocarbons from the naphthenic and paraffinic hydrocarbons. This separation is preferably effected by absorption on a solid such as silica gel, activated charcoal, etc., or liquid-liquid extraction process wherein the hydrocarbon phase is contacted with a substantially immiscible liquid phase which is a selective solvent for aromatic hydrocarbons. Suitable solvents may include S0 HF, AlCl H and other materials that tend to condense unsaturates but preferably the solvent will comprise a material chemically inert with respect to the hydrocarbon. The solvent may comprise organic liquids such as glycols, methanol, aldehydes, nitriles, dinitriles, amines, etc.

Substantially. complete removal of high boiling aromatics may be efiected by selective adsorption wherein an adsorptive solid which selectively adsorbs aromatic and unsaturated hydrocarbons is commingled with the oil. These processes may be effected continuously or with a fixed bed of material such as silica gel, activated charcoal, Attapulgus or other clays or similar materials. When a selective adsorption process is employed for aromatic removal, it may not be necessary to provide for separate sulfur removal since the selective adsorbent will remove most of the sulfur-bearing molecules in the liquid. Other means of removing the aromatic material is by converting it chemically to a more readily removable form. Therefore, treating the entire fraction with certain nitrogencontaining organic compounds such as trinitrotoluene or picric acid will cause a solid phase containing aromatic material to precipitate and acid-washing with sulfuric acid will remove the aromatic material. The preferred modes of aromatic separation are by adsorption on a solid and by solvent extracting with a selective solvent. These modes are preferred since the aromatic materials separated are not destroyed and may find other uses, and since substantially complete aromatic removal may be economically efl'ected.

The nonaromatic portion from aromatic separation zone 6 passes through line 7 to finishing zone 8. In finishing zone 8 whatever processes are required to make a complete product from the material in line 7 are efamass.

fec'ted. The processes may include, for example, fractionating the resultant lubricating oil into its various grades such as SAE 10," SAE 20, -etc'., and making suit able blends for specific purposes. Since the process of this invention produces a clean, colorless oil his not necessary to employ a clay treating or acid treating step in the finishing. The finishing zone may also include a dewaxing stage to remove wax if it'has not been previously removed or to remove wax which is formed in the process, for example, by hydrogenation of an unsaturated aliphatic molecule which was olefinic as part of the charge.

The lubricating oil resulting from this process will have excellent lubricating properties and, as will be hereinafter illustrated, the process of'the present invention produces a product havingsuperior temperature characteristics as will be indicated by the improved viscosity index of the product over the charge to this process. The viscosity index is an arbitrary measure indicating the rate of change of viscosity with temperature, with high viscosity index preferred to low viscosity index.

The following examples are presented to illustrate specific modes of operating the process of the present invention and are not intended as being unduly limiting upon the broad scope thereof.

Example I A Mid-Continent crude oil was distilled and the fraction boiling between-550 F. and 950 F. was separated and dewaxed. This fraction was then blended with hydrogen in a proportion of 1500 standard cubic feet of hydrogen per barrel of liquid and the resultant mixture was heated toa temperature of 570 F. and passed into the top of a catalyst tube at a pressure of 350 psi. The catalyst tube contained a bed of Ms x A cylindrical pellets of alumina which were impregnated with cobalt and molybdenum in a proportion of 4% by Weight of cobalt and 8% by weight of molybdenum. The proportion of cobalt and molybdenum are based on the weight of actual metal present as compared with the Weight of alumina in the catalyst and this stoichiometric measurement is intended to be for convenience of comparison rather than to indicate that the metals are in any particular form in the catalyst. The cobalt and molybdenum, which may be in the form of the pure metal, the oxide, the sulfide or mixtures of these, is disposed on the alumina pellets by soaking the pellets in solutions of the soluble salts of the metals and thereafter draining and drying the pellets thus impregnated. This impregnation may be successive, impregnating first with one and then with the other of the salts, or it may be accomplished simultaneously by impregnating with a single solution containing the salts of both metals.

The material passing from the desulfurization zone was separated into liquid and gas phases and the liquid which was stripped substantially free of hydrogen sulfide, ammonia and other normally gaseous material and passed over silica gel to remove aromatic compounds was introduced into a vessel containing a catalyst consisting of alumina pellets upon which 0.3 weight percent platinum was disposed by impregnating from a solution of chloroplatinic acid. The mixture of catalyst and oil was heated to a temperature of 650 F. and hydrogen at substantially atmospheric pressures was bubbled through this mixture from the bottom of the vessel.

The effluent from this reaction zone contains 10% aromatics and the rest of the material consists of paraffinic, isoparaihnic and alkylmononuclear naphthenic compounds.

The efiiuent from the hydrogenation and dehydrogenation zone was then passed into a tube containing silica gel and the efiiuent from the silica gel treatment was found to be substantially free of aromatic compounds. This product is Water white and requires no further treatment, except fractionation into particular boiling ranges when desired.

6 \The initial charge to the process contained-0.18 weight percent combined sulfur, 0.009 weight percent combined nitrogen and it had a viscosity index of 88.7. The product from this process contains 0.04 weight percent sulfur, it isvirtually free of combined nitrogen and the'viscosity index is 111.9. The product contains substantially no polynuclear'mate'rial and is substantially inert to hydrogenation,- dehydrogenation, dealkylation, cracking reactions and dehydrocyclization reactions at the conditions in a crank case if combined with the proper additives.

Example II Example 111 The process of Examples I and II was repeatedemploying as a hydrogenation. and dehydrogenation catalyst a composite of 0.3% platinum oxide on alumina. The hydrogenation'and dehydrogenation process resulted in an aromatic production of 18.5 weight percent aromatics which uponremoval resulted in a lubricating oil product havinga viscosity index of 112.79.

Example IV The process of the above examples was againelfected only employing this time a catalyst inthe hydrogenation and dehydrogenation zone containing 5 weight percent palladium impregnated onto activated charcoal. The product was treated by countercurrently contacting it with silica gel which resulted in the removal of the aromatic portion of the product and produced a rafiinate substantially free of aromatics having a viscosity index of 110.8.

T he products from all of the above experiments were commingled with various amounts of various viscosity index-improving additives to determine whether or not the response to such additive improvement was changed by this treatment. It was found in all cases that the improvement efllected by the additive was unchanged, that is, the addition of 2% of a viscosity index-improving additive resulted in the same increment of improvement to the product of this process as to the charge. Therefore, the gain in viscosity index that is realized is a real gain which is not diminished by poor response to additives.

From the foregoing, it may be seen that the process of the present invention provides a means for preparing a clean, high grade lubricating oil which upon addition of conventional additives has excellent lubricating qualities and is composed to retain these qualities even though subjected to severe crankcase conditions in the presence of reaction promoting material. Furthermore, the product of this process has improved temperature characteristics over the charge stock.

When lubricating oil is referred to in the specification and appended claims, it is not intended to imply that the product from this process is a complete oil. It is, however, intended that well known detergents, oxidation inhibitors and other additives may be added to perform their usual functions.

I claim as my invention:

1. A process for the manufacture of lubricating oil which comprises contacting a hydrocarbon oil fraction boiling above 550 F. and containing condensed ring naphthenes with a hydrogenation catalyst supported on a non-acidic base in the presence of hydrogen at conditions to cause dehydrogenation of condensed ring naphthenic compounds to aromatics, separating the resultant material into aromatic and nonaromatic fractions and recovering the desired lubricating oil from said nonaromatic fraction. I

2. A process for the manufacture of lubricating oil which comprises contacting a hydrocarbon oil fraction boiling above about 550 F. and containing condensed ring naphthenes with a desulfurization catalyst in the presence of hydrogen at superatmospheric pressure and at desulfurizing conditions, separating the desulfurized material into a normally liquid and a normally gaseous fraction, passing the normally liquid fraction into contact With a hydrogenation catalyst supported on a non-acidic base in the presence of hydrogen at conditions to cause dehydrogenation of condensed ring naphthenic compounds to aromatics, separating the resultant material into aromatic and nonaromatic fractions and recovering the desired lubricating oil from said nonaromatic fractions.

3. The process of claim 1 further characterized in that said hydrogenation catalyst comprises platinum and alumina.

4. The process of claim 1 further characterized in that said hydrogenation catalyst comprises platinum deposited on a base of alumina and magnesium oxide.

5. The process of claim 1 further characterized in that said hydrogenation catalyst comprises platinum deposited upon a carbonaceous base. I

6. The process of claim 1 further characterized in that said hydrogenation catalyst comprises palladium impregnated alumina.

7. The process of claim 1 further characterized in that said dehydrogenation is effected at a temperature of from about 500 F. to about 900 F.

8. The process of claim 2 further characterized in that said desulfurization is effected at a temperature of from about 450 F. to about 600 F.

9. .The process of claim 2 furthercharacterized in that said desulfurization catalyst comprises cobalt, molybdenum and alumina.

10. A process for manufacturing lubricating oil which comprises contacting a hydrocarbon oil fraction boiling above about 600 F. and containing condensed ring naphthenes with a desulfurization catalyst comprising cobalt, molybdenum and alumina in the presence of hydrogen at superatmospheric pressure and at a temperature of from about 450 F. to about 600 F., separating the desulfurized material into a normally liquid and a normally gaseous fraction, passing the normally liquid fraction into contact with a hydrogenation catalyst comprising platinum supported on alumina and magnesium oxide at a temperature of from about 500 F. to about 900 F. in the presence of hydrogen to convert the condensed ring naphthenes to aromatics, separating the resultant material into aromatic and nonaromatic fractions and recovering the desired lubricating oil from said nonaro-. matic fraction.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Rossini et al.: Progress in Petroleum Technology (ACS #5), 1951, Amer. Chem. Soc., Wash., DC, pp. 334352 (p. 350 only relied on).

France Dec. 23, 1953 

2. A PROCESS FOR THE MANUFACTURE OF LUBRICATING OIL WHICH COMPRISES CONTACTING A HYDROCARBON OIL FRACTION BOILING ABOVE ABOUT 550*F. AN DCONTAINING CONDENSED RING NAPHTHENES WITH A DESULFURIZATION CATLAYST IN THE PRESENCE OF HYDROGEN AT SUPETMOSPHERIC PRESSURE AND AT DESULFURIZING CONDITIONS, SEPARATING THE DESULFURIZED MATERIAL INTO A NORMALLY LIQUID AND A NORMALLY GASEOUS FRACTION, PASSING THE NORMALLY LIQUID FRACTION INTO CONTACT WITH A HYDROGENATION CATALYST SUPORTED ON A NON-ACIDIC BASE IN THE PRESENCE OF HYDROGEN AT CONDITIONS TO CAUSE DEHYDROGENATION OF CONDENSED RING NAPHTHENIC COMPOUNDS TO AROMATICS, SEPARATING THE RESULTANT MATERIAL INTO AROMATIC AND NONAROMATIC FRACTIONS AND RECOVERING THE DESIRED LUBRICATING OIL FRM SAID NONAROMATIC FRACTIONS. 